The present invention relates to autonomous landing system for landing or assisting the landing of aircraft under utilization of navigational devices, equipments and systems and more particularly the invention relates to a new use of methods and equipment as proposed by some of use and another, as per the applications of common assignee Ser. No. 523,130, filed May 14, 1990, Ser. No. 523,131, filed May 14, 1990, now respectively U.S. Pat. Nos. 5,087,916 and 5,047,777. The content of these applications is incoporated by reference to its entirety in this application.
Automatically operated landing system for aircraft are known by and in themselves and have been introduced into the practice of operating aircraft. The otherwise known systems are based on position measurement under utilization of electromagnetic waves and are known e.g. under the designation of instrument landing systems (ILS) or the so called microwave landing systems (MLS). These systems require certain infrastructural devices, i.e. ground based features and equipment and facilities in or near the respective airports including particularly transmitters and receivers.
An autonomous system as far as the aircraft in general is concerned and concerning the on-board equipment in particular must meet two requirements. In other words, the basic requirement can be divided in two aspects. First of all, one needs a system for extremely accurately measuring the three spatial coordinates, for example cartesian coordinates x,y,z with reference to a coordinate system based in and at the point of landing. On the other hand one needs an on-board computing facility which calculates the approach trajectory on the basis of aircraft performance, its features and characteristics and under consideration of safety factors of involving the particular craft and being further related to particulars such as the geographic and weather situation of the landing site. The on-board computer calculates the steps to be taken as far as controlling the aircraft is concerned and provides the requisite signals for the control of actuators for the rudders, electrodes etc. Aircraft which do not provide for automatic landing use of course the pilot's skill in this regard. It is practical to consider the pilot as a "man in the loop" in that he or she receives a significant amount of information as landing assist. Here of course it is particularly desirable to provide the pilot as accurately as possibly with objective data concerning the position of the craft, over and beyond his ability to see the approaching landing site.